The Paul-Ehrlich-Institut, in cooperation with the University of Frankfurt am Main, examined the long-term antibody response after SARS-CoV-2 infection in 828 people with different degrees of COVID-19. The study measured binding antibodies against a range of SARS-CoV-2 target antigens, neutralising antibodies, and antibody binding strength (antibody avidity). Sensitivity, kinetics, and the duration of antibody detection depended on the detected antibody type, test design, target antigen of the anti-SARS-CoV-2 antibody test, antibody avidity, and COVID-19 severity. The Journal of Clinical Virology reported on the results in its online edition from 4 December 2021.